我似乎不能让这个工作。我的作业只允许我们使用JTextAreas。我的代码的问题是,我不能读取它的文本在TextArea。目标是在用户输入输入后输入ENTER后运行逻辑。
当我运行代码时,我只能输入一个字符。GUI显示的字符在零之后,原因我不知道。示例:[0b]将在TextArea中。请帮帮我,我想不明白。
public class ArabicToRomanGUI extends JFrame
{
private static final long serialVersionUID = 1L;
private JTextArea enterRomanNumber = new JTextArea();
JLabel label = new JLabel();
JPanel panel = new JPanel();
JFrame frame = new JFrame();
//TestArea contructor adds jtextArea to jframe
public ArabicToRomanGUI()
{
super("Convert a Roman Numeral");
setLayout(new FlowLayout());
//Text field to enter a roman numeral
enterRomanNumber = new JTextArea(1,25);
enterRomanNumber.setText("Delete this text and Enter a Roman Numerial Here!");
//enterRomanNumber.setAlignmentX(0);
//enterRomanNumber.setAlignmentY(0);
add(enterRomanNumber);
HandlerForTextArea handler = new HandlerForTextArea();
enterRomanNumber.addKeyListener(handler);
}
private class HandlerForTextArea implements KeyListener
{
//used to process text field events
@Override
public void keyTyped(KeyEvent e)
{
String userInput = "";
userInput = enterRomanNumber.getText();
userInput = userInput.toUpperCase();
ConversionLogic.ConvertFromRomanToArabic(userInput); //converts user string of Roman numerals to an int in arabic
String arabicNumberAsString = ConversionLogic.getConvertedRomanNumeral();
enterRomanNumber.setText(arabicNumberAsString);
//user pressed enter in JTextField enterNumberField
if(e.getKeyCode() == KeyEvent.VK_ENTER)
{
//enterRomanNumber.setText(arabicNumberAsString);
if (ConversionLogic.getCheckFail() == true)
{
JOptionPane.showMessageDialog(frame, "The Roman Numeral entered is Invalid", "Error", JOptionPane.ERROR_MESSAGE);
}
else
{
JOptionPane.showMessageDialog(frame, "The arabic equivalent is " + arabicNumberAsString + "." , "Conversion Successful", JOptionPane.PLAIN_MESSAGE);
}
}
}
@Override
public void keyPressed(KeyEvent e) {
//not used
}
@Override
public void keyReleased(KeyEvent e) {
//not used
}
}//end inner class TextFieldHandler
}//end class ArabicToRomainGUI
正如您将在本网站反复阅读的那样,不要将KeyListener
与JTextArea
这样的文本组件一起使用,因为这会使文本组件的功能混乱。相反,当您希望检测JTextArea
状态发生变化后,请使用DocumentListener
,或者如果您希望检测(并可能更改)文本组件在发布到文本组件之前的更改,请使用DocumentFilter
。
我看到你正在使用JTextArea(1,25)或单行JTextArea
,这让我问:为什么不使用JTextField
?如果您这样做并希望捕获ENTER键按下,那么您可以简单地将ActionListener
添加到JTextField
。